At one time, a cigarette packing line produced packets of cigarettes of one brand with no changes over a prolonged period of time. More recently, attempts have been made to adopt a so-called “just in time” practice, whereby the brand produced on a given cigarette packing line is changed frequently to real-time adapt to market demand and so reduce storage. As a result, automatic packing machines producing packets of cigarettes now undergo increasingly frequent brand changes.
Brand changing on an automatic packing machine producing packets of cigarettes normally comprises two types of intervention: “mechanical” or “hardware” changes, which consist in physically adjusting the component parts of the packing machine and/or changing component parts incompatible with the new brand; and “logic” or “software” changes, which consist in replacing the old-brand configuration with that of the new brand in the control unit of the packing machine. Brand configurations are the values of the parameters controlling the electrically controlled operating parts of the packing machine to produce the brand. In other words, the packing machine comprises various electric/electronic operating parts (i.e. electrically controlled parts, such as servovalves, electric actuators, sensors, heating resistors), each controlled by a control algorithm implemented by the control unit and which employs control parameters whose values may vary depending on the brand for production (e.g. the sealing temperature of a heating resistor may vary depending on the packing material used, or the movement of an electric actuator may vary depending on the size of the packet of cigarettes for packing, or the characteristics of the packing materials). To produce a given brand, the control unit must therefore be given the corresponding configuration, i.e. the corresponding values of the parameters controlling the electrically controlled operating parts of the packing machine.
On currently marketed automatic packing machines, all the producible brand configurations are memorized in a bulk storage memory of the control unit, in which each configuration is memorized and controlled as a single, indivisible database containing all the parameter values controlling the electrically controlled operating parts. And the most common way of creating a new configuration, for example, is to duplicate (i.e. “copy & paste”) the existing configuration most closely resembling the new one, and then alter certain parts of the duplicate.
The above configuration control method has the advantage of being extremely straightforward and intuitive, but is not very efficient, on account of the configurations being completely unrelated and independent, regardless of the resemblance between them. That is, if two only slightly different configurations, e.g. 3 out of 500 values, are required, two separate, almost identical databases must still be created in the control unit bulk storage memory. And if either of the configurations is updated slightly at a later date to improve the production process (as frequently occurs in the case of packing processes), it is desirable that the same updates also be copied in the other configuration. Otherwise, the benefits of the improvement are not extended to all the configurations, and, more importantly, the configurations operate differently, thus seriously complicating maintenance, adjustment, and production process improvement. At each configuration update, the operator should therefore determine whether the same also applies to the other configurations. But since this is a long, painstaking job (especially when numerous configurations are involved) and potentially subject to error, very often it is not done.